Multi-barrel carburetor



1961 H. A. CARLSON ErAL 3,006,616

MULTI-BARREL CARBURETOR 5 Sheets-Sheet i Filed Jan. 5, 1959 FIG.

FIG.2.

INVENTORS HAROLD A. CARLSON OLIN J. EICKMANN ROBERT J. SMITH ATTORNEYOct. 31, 1961 H. A. CARLSON EFAL 3,

MULTI-BARREL CARBURETOR Filed Jan. 5. 1959 5 Sheets-Sheet 2 INVENTORSHAROLD A. CARLSON OLIN J. EICKMANN ROBERT J. SMITH ZLM W ATTORNEY Oct.31, 1961 Filed Jan. 5, 1959 H. A. CARLSON ETAL MULTI-BARREL CARBURETOR 5Sheets-Sheet 4 HAROLD A.CARL SON OLIN J. EICKMANN BY ROBERT SMITHATTORNEY I Oct. 31, 1961 H. A. CARLSON ETAL 3,006,616

MULTI-BARREL CARBURETOR Filed Jan. 5. 1959 5 Sheets-Sheet 5 INVENTORSHAROLD A. CARLSON OLIN J. EICKMANN ROBERT J. SMITH pgiww w ATTORNEYUnited States Patent 3,006,616 MULTI-BARREL CARBURETOR Harold A.Carlson, Brentwood, Olin J. Eickmann, St. Louis, and Robert J. Smith,St. Anns, Mo., assignors to ACF Industries, Incorporated, New York,N.Y., a corporation of New Jersey Filed Jan. 5, 1959, Ser. No. 784,986 8Claims. (Cl. 261-23) The invention relates to carburetors for internalcombustion engines, and more particularly to multi-stage carburetorsespecially for automotive engines.

It will be understood that a multi-stage carburetor comprises a primarysection and a secondary section, each adapted to be supplied with fuelfor admixture with air flowing therethrough to the engine on which thecarburetor is used. In a typical multi-stage carburetor, the primarysection comprises two primary mixture conduits or barrels, and thesecondary section comprises two secondary mixture conduits or barrels,this type of carburetor accordingly being referred to as a four-barrelcarburetor. The primary section is operative throughout the entire powerof range of the engine. The secondary section is operable only in theupper part of the power range to supplement the primary section. Eachbarrel has a nozzle supplied with fuel from a fuel bowl. It is desirable.to have the discharge ends of the nozzles located as high as possiblein the respective barrels to provide for more uniform and consistentflow of fuel and to avoid surging of fuel through the nozzles, as mayoccur, for example, when the vehicle makes a sharp turn. While it ispossible to locate the discharge ends of the secondary nozzlesrelatively high in the secondary section, it is usually not possible tolocate the discharge ends of the primary nozzles as high as thedischarge ends of the secondary nozzles, because of the provision of achoke valve in the primary section. In such case, if a primary nozzleand a secondary nozzle are supplied with fuel from a bowl in which thelevel of fuel is the same for both nozzles, the lift (the difference inelevation of the fuel level and the nozzle discharge end) is greater forthe secondary nozzle than for the primary nozzle. This results isdisproportionate flow of fuel to the primary and secondary nozzles.

Accordingly, it is an object of this invention to provide a multi-stagecarburetor having means providing separate reservoirs of fuel for aprimary nozzle and a secondary nozzle with fuel maintained at differentlevels in the two reservoirs more nearly to equate the primary andsecondary lifts to tend to provide more proportionate flow of fuel tothe nozzles.

A further object of the invention is the provision of an economicalcarburetor construction for the purpose described in which only onefloat is used for control of fuel level in the reservoirs.

As above stated, a typical multi-stage carburetor is a four-barrelcarburetor having two primary barrels and two secondary barrels. Afurther object of this invention is the provision of a multi-stagecarburetor having a higher capacity in the upper power range than thetypical fourbarrel carburetor. This is attained in a construction havingsix mixture conduits or barrels, of which two are pri- 1 3,006,616Patented Oct. 31, 1961 In the accompanying drawings, in which one ofvarious possible embodiments of the invention is illustrated,

FIG. 1 is a left side elevation of a multi-barrel carburetor, inaccordance with the invention.

FIG. 2 is a right side elevation of the carburetor of FIG. 1 with partsbroken away and shown in section.

FIG. 3 is a plan view of the carburetor of FIG. 1 with parts broken awayand shown in section.

FIGS. 4, 5, 6, 7 and 8 are cross sections taken on lines 44, 55, 66, 7-7and 8--8, respectively, of FIG. 3.

FIG. 9 is a horizontal section taken on line 99 of FIG. 5.

FIG. 10 is an enlarged fragment of FIG. 6.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

Referring to the drawings (FIGS. 1 and 8), there is indicated at .1 inFIG. 1 an automotive vehicle having an engine 3 on which is a six-barrelcarburetor 5 of this invention. Fuel is supplied to the carburetor froma fuel tank of the vehicle. A pump operated by the engine is adapted topump fuel to the carburetor through a line 15. The carburetor 5, whichhas two vertical primary barrels and four vertical secondary barrels, ismounted on the intake manifold 17 of the engine, and is shown in FIG. 5with an air filter 19 mounted thereon.

The carburetor 5, comprises a main body casting 21 which is referred toas the float bowl section, an upper section 23 which is referred to asthe air horn section, and a lower section 25 which is referred to as thethrottle body section. The float bowl section 21 is generallyrectangular in plan, having front and back walls designated 27 and 29,and left and right side walls designated 31 and 33. It is formed toprovide two fuel containers, one at each side, each of which is dividedinto three individual fuel bowls or reservoirs (FIG. 3). The three bowlsat the left side are designated 35L, 37L and 39L. Bowl 35L is thecentral one of these three bowls, bowl 37L is the forward one of thethree, and bowl 39L is the rearward one of the three. These bowls aredefined by an inner left wall 41 extending parallel to the left sidewall 31 from the front wall 27 to the back wall 29 of the float bowlsection 21 and by forward and rearward crosspartitions 43L and 45Lextending between walls 31 and 41. The three bowls at the right side aresimilar to those at the left and are designated 35R,37R and 39R. Theyare defined by an inner right wall 51 extending parallel to the rightside wall 33 from the front wall to the back wall of the float bowlsection and by forward and rearward cross- -partitions 43R and 45R(similar to partitions 43L and 45L) extending between walls 33 and 51.

The region of the float bowl section between the walls 41 and 51 isformed to provide two vertical primary mixture conduits or barrels SSLand 55R and four vertical secondary mixture conduits or barrels 57L,57R, 59L and 59R (FIG. 3). The primary barrels SSL and 55R are locatedside-by-side generally centrally of the float bowl section, the barrel55L being the left-hand primary barrel, and the barrel 55R being theright-hand primary barreL- The second-ary barrels 57L and 57R arelocated side-by-side forward of the primary barrels, the barrel 57Lbeing the left-hand forward secondary barrel and the barrel 57R beingthe right-hand forward secondary barrel. The secondary barrels 59L and59R are located side-by-side rearward of the primary barrels, the barrel59L being the left-hand rearward secondary barrel, and the barrel 59Rbeing the right-hand rearward secondary barrel. The two primary barrelsSSL and 55R are identical, each being formed as indicated at 61 in FIGS.5 and 8 toconstitute a main venturi. The four secondary barrels areidentical, each being cylindrical with an enlarged upper end portion 63providing an upwardly facing shoulder 65 (see FIG. 5). i

The six fuel bowls 35L, 37L, 39L, 35R, 37R and 39R all have the samewidth laterally of the carburetor, but the forward and rearward bowls37L, 39L, 37R and 39R are shorter in front-to-rear dimension than thecentral bowls 35L and 35R (FIGS. 3, 4, and 8). The upper edges of thecross-partitions 43L, 45L, 43R and 45R are below the top of the floatbowl section 21 and constitute weirs W over which fuel is adapted tooverflow from the respective forward and rearward bowls into therespective central bowl. The left-hand forward bowl 37L is locatedalongside of and is adapted to supply the lefthand forward secondarybarrel 57L. The left-hand central bowl 35L is located alongside ofand isadapted to supply the left-hand primary barrel 55L. The left-handrearward bowl 39L is located alongside of and is adapted to supply theleft-hand rearward secondary barrel 59L. The right-hand forward bowl 37Ris located alongside of and is adapted to supply the right-hand forwardsccondary barrel 57R. The right-hand central bowl 35R is locatedalongside of and isadapted to supply the righthand primary barrel 55R.The right-hand rearward bowl 39R is located alongside of and is adaptedto supply the rearward right-hand secondary barrel 59R..

The air horn section 23 is formed to provide a roundedcorner rectangularair horn 67 through which air may enter and flow downward through thesix barrels. The air horn 67 has aforward cross-partition .69 and arearward cross-partition 71 dividing it to form a forward air inlet 73for the two forward secondary barrels, a central air inlet 75 for thetwo primary barrels, and a rearward air inlet 77 for the two rearwardsecondary barrels. .The air horn section 213 is also formed with lateralfloat bowl cover portions 79L and 79R for the three left-hand bowls andthe three right-hand bowls (FIG.. 3). The three bowls at each side arevented into the air horn 67 via a vent passage 81 in the air hornsection and a vent tube 83 (see FIGS. 3 and 8). Each of the bowl coverportions 79L and 79R of the air horn section 21 is formed with a raisedrib 85 extending from the rear thereof toward the front (FIGS. 3 and 4).Each of these ribs has .a rearward fuel inlet passage such as indicatedat 87 in FIG. 4. The air horn section 2 1 is also formed with .arearward cross-rib 89 in which is a fuel passage 91 connecting theleft-hand fuel inlet passage 87 and the right-hand fuel inlet passage87. The fuel supply line .15 is connected into the rearward end 90 ofthe left- -is a valve port 95 which opens downward into a bottom recess97 in the respective bowl cover portion 79L or 79R of the air hornsection 21. This recess 97 is located above the respective rearward bowl39L or 39R,

as the case may be. Pivoted at 99 in each rearward bowl is a float arm101. Secured to this arm is a bracket B having a portion which extendsup and over the respective weir W and into the central bowl, where itcarries a float 105. A needle valve member 107 is vertically slidable ina guide 109 at the lower 'end of the recess 97. This guide has openingssuch as indicated at 111 for flow of fuel down into the rear bowl. Thelower end of the needle valve member 107 engages the bracket 103, andits 'upper end is engageable wtih the valve seat defined by the lowerend of the valve port 95. Extending forward and downward from the upperend of the recess 97 in each fuel bowl cover portion 79L and 79R of theair horn section 21 is a fuel passage 113 which extends over the centralbowl and opens downward at its forward 'end above the forward bowl. Asto each side of the carburetor, the needle valve member 107 closes whenthe fuel in the central bowl 35L or 35R, as the case may be, reaches apredetermined head or level L1 below the weirsW. When the fuel level inthe central bowl falls below this predetermined level L1, the valvemember opens. Fuel then flows down through the valve port 95 and therecess 97 into the rearward bowl. Fuel also flows through the passage113 to the forward bowl. The flow of fuel continues until the forwardand rearward bowls fill up, and then fuel flows over the weirs W intothe central bowl to bring up the fuel level in the latter to the levelL1. Thereupon the needle valve member 107 closes to cut off the flow.Thus, a higher fuel level L2 is maintained in the forward and rearwardbowls than in the central bowl. The fuel level L2 in the forward andrearward bowls corresponds to the height of the weirs W, the float beingadjusted so that fuel level L1 in the central bowl is below the level ofthe weirs.

The throttle body section 25 is provided with two primary throttle boressuch as indicated at 115 which register with the lower ends of theprimary barrels SSL and 55R (FIGS. 5 and 8). The throttle body section25 is also provided with two forward secondary throttle bores such asindicated at 117 which register with the lower ends of the two forwardsecondary barrels 57L and 57R, and with two rearward secondary throttlebores such as indicated at 119 which register with the two rearwardsecondary barrels 59L and 59R. Journalled in the throttle body section25 and extending laterally across the two primary throttle bores 115 isa primary throttle shaft 121. This primary throttle shaft carries 'aprimary throttle valve 123 in the left-hand primary throttle bore, and asimilar primary throttle valve 123 in the right-hand primary throttlebore. Fixed 'on the left-hand end of the primary throttle shaft 121 areinner and outer primary throttle arms 125 and 127 (see FIG. 1).Journalled in the throttle body section 25 and extending laterallyacross the two forward secondary throttle bores 117 is a forwardsecondary throttle shaft 129. This carries a secondary throttle valve131 in the left-hand forward secondary throttle bore 117 and a similarsecondary throttle valve 131 in the righthand forward secondary throttlebore. Iournalled in the throttle body section 25 and extending laterallyacross the two rearward secondary throttle bores 119 is a rearwardsecondary throttle shaft 133. This carries a secondary throttle valve135 in the left-hand rearward secondary throttle bore, and a similarsecondary throttle valve'135 in the right-hand rearward secondarythrottle bore.

The left-hand central bowl 35L is the source of fuel for a left-handprimary high speed system and a lefthand low speed system for supplyingfuel to the left-hand primary barrel 55L. The right-hand central bowl35R is the source of fuel for a right-hand primary high speed system anda right-hand low speed system for supplying fuel to the right-handprimary barrel 55R. The leftand right-hand primary highspeed systems areidentical, and a description of the left-hand primary high speed systemwill suflice for both. As shown in FIG. 6, the float bowl section 21 isformed with a well 137 extending down from its top in the wall 41adjacent the rear of the central bowl 35L. A slot 139 (see FIG. 4) isprovided in Wall 41 for communication between the central bowl'35L andthe upper portion of the well. This slot 139 extends down below fuellevel L1 for flow of fuel from the central bowl into the well. Towardthe bottom of the well is a primary metering jet 141 (see FIG. 6). Belowthis jet there is a horizontal passage 143 to a vertical recess 145 inthe wall 41 extending up from the bottom of the float .bowl section 21between the central bowl 35L and the primary barrel 55L. This recess 145is closed at the bot torn by the throttle body section 25 (FIG. 8) Flowof fuel through the metering jet 141 to the recess 145 is under controlof a step-up rod 147 which extends down from a pocket 149 in the airhorn section 23 through a hole 151 in the air horn section. At its upperend, the step-up rod is bent to have a horizontally extending arm 153which is received in a piston 155. This piston is slidable in a verticalcylinder 157 provided in the air horn section and is biased upward by aspring 159. There is an opening 161 at the lower end of the cylinder 157which registers with the upper end of a vacuum passage 163 in the floatbowl section 21. The lower end of the vacuum passage 163 registers withthe upper end of a vacuum passage 165 in the throttle body section 25.The vacuum passage 165 has a horizontal portion 167 opening into thethrottle bore 115 in the throttle body section below the primarythrottle valve 123. The lower end of the step-up rod 147 is formed sothat, upon increase of vacuum below the piston 155, with resultantdownward movement of the piston and the rod, the flow of fuel throughthe jet 141 is restricted, and vice versa. A cover cap for the pocket149 is indicated at 169.

At the upper end of each primary barrel is a primary venturi 171 on aprimary venturi arm 173 (FIGS. and 8). This arm 173 extends into thebarrel from the side thereof toward the respective central bowl. The armhas a passage 175 in which is pressed a fuel nozzle 177. This nozzleprojects into the primary venturi 171. The passage 175 extends from anopening 179 above the recess 145. A perforated main fuel tube 181extends down from the opening 179 into the recess 145. During high speedoperation (i.e., with the primary throttles 123 open), fuel flows fromthe left-hand central bowl 35L to the left-hand primary barrel 55L viaslot 139, well 137, jet 141, and passage 143 to recess 145, thencethrough the main fuel tube 181 and out through nozzle 177 into theprimary venturi'171. The high speed system for supplying fuel from theright-hand central bowl 35R to the right-hand primary barrel 55R isidentical.

The leftand right-hand low speed systems are identical, and adescription of the right-hand low speed system will sufiice for both. Asshown in FIG. 8, an idle tube 183 extends down in the recess 145 from ahole 185 which extends down from the top of the float bowl section 21.The upper end of this hole 185 registers with a vertical hole 187 in theair horn section 23. From this vertical hole 187 there is a horizontalpassage 189 (see FIGS. 3 and 8) in the air horn section to a verticalhole 191 (see FIGS. 3 and 5) which extends up from the bottom of the airhorn section. This latter hole 191 registers with a vertical hole 193extending through the float bowl section. Hole 193 opens at its lowerend into a recess 195 (FIGS. 5 and 9) in the throttle body section 25,from which there is an idle discharge port 197 opening into the primarythrottle bore 115. An idle adjusting screw 199 (see FIG. 9) is threadedin a horizontal hole 201 which leads into the recess 195 below the idledischarge port 197. An idle needle port 203 leads into the primarythrottle bore 115 from the hole 201. An air bleed hole 205 (see FIG. 5)leads into the upper end of the vertical hole 191.

An accelerating pump indicated at 207 is provided for discharging fuelinto the primary barrels at their upper ends during acceleration fromlow speeds. As appears in FIGS. 3, 6 and 10, this pump comprises aplunger rod 209 operable in a vertical cylinder 211 formed in the Wall41 adjacent the rearward end of the left-hand forward bowl 37L. Thiscylinder 211 extends down from the top of the float bowl section 21 andis covered by the air horn section 23. The rod 209 extends down into thepump cylinder 211 from the air horn section 23 through a hole 213 in thebottom of the latter. The rod 209 has spaced heads 215 and 217 at itslower end, head 215 being the upper one of the heads and head 217 beingthe lower.

The rod has a packing member generally designated 219 retained thereonby the heads 215 and 217. This packing member is made of a flexibleresilient elastomeric material in the form of an inverted cup, having asubstantially flat circular top wall 221 and an annular skirt portion223 of downwardly flaring conical form. The top wall 221 is providedwith a central hole which may be a square hole, the portion of the rodbetween the heads (which may be cylindrical) being freely slidablyreceived (FIGS. 2, 3, 6, and 7).

in this hole. The packing member is preferably formed from sheetmaterial composed of polymerized tetrafluoroethylene such as is soldunder the trade designation Teflon, having a thickness less than thespacing of the heads 215 and 217. The packing member is mounted on theportion of the rod between the heads with its annular skirt portion 223extending downward surrounding the lower head 217. The dimensions of thepacking member are initially such that the skirt as received in thecylinder is radially compressed so as to have a sliding sealing fit inthe cylinder 211.

The top wall 221 of the packing member 219 is provided with holes suchas indicated at 225, these holes being located radially outward from thecenter hole. The top wall 221 of the packing member is slidab le on therod between the relatively lowered position in which it is shown in FIG.10 in flatwise engagement with the lower head 217 and a relativelyraised position in flatwise engagement with the upper head 215. In theraised position, holes 225 are closed by the upper head 215. The lowerhead 217 is provided with an annular series of holes such as indicatedat 227 (which may be arcuate slots) with which the holes 225 registerwhen the top wall 221 of the packing member is in the lowered position.The rod 209 has an axial passage 229 extending up from its lower end andtransverse holes such as indicated at 231 traversing the portion thereofbetween the heads 215 and 217 and intersecting passage 229 providinglateral ports opening from passage 231 to the space between the heads215 and 217.

The rod 209 is biased downward by a coil compression spring 233 reactingfrom the bottom of the air horn section 23 against the upper head 215.The rod 209 is linked to the primary throttle shaft 121 to be pulled upagainst the bias of the spring 233 when the primary throttle valves 123are closed by means of a linkage such as shown in FIG. 1 i'ndluding alink 235 connecting the outer primary throttle arm 127 to a pump rocker237 pivoted at 239 on the air horn section 23, and a ling 239aconnecting rocker 237 to the upper end of the rod 209. Fuel is suppliedto the pump cylinder 211 above the packing member 219 from the left-handforward bowl 37L via a passage 240 (see FIG. 4). Fuel is discharged fromthe pump cylinder on downward movement of the rod 209 through adischarge passage 241 (FIGS. 3 and 6) leading from the lower end of thecylinder to a pump jet cluster 243 located forward of and between thetwo primary barrels SSL and 55R and including two jets 245 fordischarging pumped fuel into the two primary barrels. When the rod 209is driven downward upon opening of the primary throttle valves, thepacking member 219 occupies the raised position in which its top wall221 engages the upper head 215 and holes 225 are closed. When the rod209 moves upward on closing the primary throttle valves, the packingmember slides down relative to the rod to its lowered position in whichholes 225 are opened for flow of fuel from above the packing member tobelow the packing member to prime the pump. A 'disch-arge check valvemay be incorporated in passage 241.

Journalled in the air horn section 23 and extending laterally across thecentral air inlet 75 for the two primary barrels SSL and 55R is a chokevalve shaft 247 This carries a choke valve 249 for both primary barrels.There are no choke valves for the secondary barrels. Secured on theright end of the choke shaft 247 is an am 251 (see FIG. 2). Mounted onthe right side of the float bowl section 21 is an automatic chokecontrol housing 253. This contains thermostatic coil 255 controlling alever 257 on a shaft 259. At 261 is indicated at choke piston slidablein a choke cylinder 263. Link 265 connects the choke piston 261 andlever 257. The vacuum port for choke cylinder 263 is indicated at 267.The hot air inlet for the housing is indicated at 269 and is connectedto a heat pocket or stove 7 on the exhaust manifold of the engine 3. Alink 274 conmeets a lever 577 fired to shaft 259'to arm 251.

At the upper end of each secondary barrel 57L, 57R, 59L and 59R is'asecondary venturi cluster designated in its entirety by the referencecharacter 275 (FIGS. 3 and This includes a ring 277 which seats on theshoulder 65 and which is formed to provide a main venturi, and anupwardly angled arm 279 extending toward the center of the ring andcarrying a boost venturi 281. In view of the upward angling of the arms279, the boost venturis are located at a higher elevation than theprimary venturis 171 in the primary barrels SSL and 55R. This will beapparent from FIGS. 5 and 7. Each cluster 275 includes a block 283seated in a recess 2S5 therefor in the float bowl section 21 (FIGS. 3, 6and 7). For each secondary barrel there is a secondary'fuel systemincluding a vertical hole 287 (FIG. 6) in the float bowl section 21extending up to the bottom of'the block 283. Hole 287 is closed at thebottom by the throttle body section The block 283 has a vertical hole289 of smaller diameter than'hole 287 extending up from its bottom. Afuel tube 291 extends down from hole 289 into the hole 287. Each clusterhas a hole 293 extending through its arm 279 to the hole 289, with afuel nozzle 2'95 pressed in the hole 293 and'projecting into the boostventurl 281. The upper discharge ends of these secondary nozzles 295 arehigher than the discharge ends of the primary nozzles 177 (FIG. 5). Asto each secondary barrel, fuel is supplied to the lower end of therespectivehole 287 from the respective secondary supply bowl (37L, 37R,39L, 39R, as the case may be) through a secondary system passage 297(FIGS. 3 and 6). In the hole 287 above this passage 297 is a meteringjet 299.

Iourn-alled in the float bowl section 21 and extending laterally acrossthe two forward secondary barrels 57L and 57R is a forward velocityvalve shaft 301 (FIGS. 3, 5 and 7). This carries a velocity valve 303 inthe left-hand forward secondary barrel 57L and a similar velocity valve303 in the right-hand forward secondary barrel 57R. Journalled in thefloat bowl section '21 and extending laterally across the two rearwardsecondary barrels 59L and 59R is a rearward velocity valve shaft 305.This carries a velocity valve 307 in the lefthand rearward secondarybarrel 59L and a similar velocity valve 307 in the right-hand rearwardsecondary barrel 59R. The forward velocity valve shaft 301 is biased torotate in valve-closing direction by a clock spring 309 located in apocket 311 in the float bowl section 21 between the forward secondarybarrels. The rearward velocity valve shaft 305 is biased to rotate invalve closing direction by a similar clock spring 313 located in asimilar pocket 315 in the float bowl section between the rearwardsecondary barrels.

Referring to FIGS. 1 and 3, the outer primary throttle arm 127 is shownto carry a fast idle adjusting screw 317 engageable with a fast idle cam319 pivoted at 321 on the left side Wall 31 of the float bowlsection 21.The choke shaft 247 has an arm 323 fixed on its left 'end. A link 325connects arm 323 to a lever 327 pivoted at 321 along with cam 319..Lever 327 has a lateral lug 329 engageable by the cam. A coil spring 331biases the cam to rotate clockwise toward engagement with this lug. Asthe choke valve opens, arm 323 swings counterclockwise as viewed in FIG.1, the lever 327 is rotated clockwise to let off the cam 319, whichfollows lever 327 around. The lever 327 has a second lug 333 whichextends through a notch 335 in the cam under one end of the spring 331.A secondary lockout lever 337 is also pivoted at 321 on the left sidewall of the float bowl section 21. This is. gravity-biased towardlatching engagement with a lug 339 on the rearward secondary throttleshaft 133, and is engageable by the -lug 329 to be swung out of latchingengagement with lug 339 when the lever 327 is swung clockwise on open-:ing of. the choke valve. When the primary throttle valves are fullyopened, a lug 341 on the end of the inner throttle arm 125 engages cam319 to rotate the cam and the lever 327 clockwise, thereby partially toopen the choke valve for unloading purposes. An idle speed screw 343 isthreaded in a lug 345 on the left side wall 31 of the float bowl section21. This is engageable by a lug 347 on the inner primary throttle arm125.

Referring to FIGS. 2 and 3, the primary throttle shaft 121 is shown tohave an inner arm 349, a dog 351 and an outer arm 353 at its right end.The inner arm 349 and the dog 351 are rotatable relative to the shaft121 and to one another. The outer arm 353 is fixed to the shaft .121.The dog has a first lateral lug 355 engageable with the outer arm 353and a second lateral lug 359 engageable with the inner arm 349. A coilspring 361 biases the dog to rotate in the direction for engagement ofits lug 355 with the outer arm 353. A link 363 connects the inner arm349 and an arm 365 fixed on the right end of the rearward secondarythrottle shaft 133. A coil spring 367 is provided for biasing therearward secondarythrottle valves 135 closed. A link 369 connects arm365 to an arm 371 fixed on the right end of the forward secondarythrottle shaft 129, so that the latter operates in unison with therearward secondary throttle shaft 133. When the primary throttle valves123 are opened, the outer arm 353 rotates counterclockwise as viewed inFIG. 2 along with the primary throttle shaft 121. Dog 351 (having lugs357 and 359) thereon follows the arm 353 around under the bias of spring361. When the primary throttle valves have been opened a predeterminedamount (50, for example), lug 359 comes into engagementwith the innerarm 349 and rotates it counterclockwise. This results in opening of theforward and rearward secondary throttle valves 131 and 135. Thesecondary throttle linkage is so proportioned that the secondarythrottle valves operate in unison and in phase and arrive at their wideopen position at the same time as the primary throttle valves. A shoe373 on arm 365 is engageable with a shoe 375 on arm 353 to precludeopening of the secondary throttle valves until the primary throttlevalves have been opened approximately the stated predetermined amount.

Operation is as follows:

The four secondary bowls 37L, 37R, 39L and 39R hold fuel up to the levelL2 of the weirs W, but the two primary bowls 35L and 35R hold fuel onlyup to the level L1 below the level L2 as determined by the float 105.Thus, while the discharge ends of the four secondary nozzles 295 at ahigher elevation than the discharge ends of the primary nozzles 177, byappropriate positioning of the float 105 relative to the float arm 101,

'the lifts for the primary nozzles and the secondary nozthan the liftfor the primary nozzles, and the flow to the (which may be referred toas primary bowls) through primary nozzles would accordingly bedisproportionately greater than the flow to the secondary nozzles.

The primary throttle shaft 121 is operated by the vehicle pedal,connection being made to the inner primary throttle am 125 below theshaft 121. The primary throttle shaft 121 is biased in primary throttlevalve closing direction (which is counterclockwise as viewed in FIGS. 1and 5) by the pedal return spring. When the pedal isdepressed, theprimary arms 125 and 127 and the primary throttle shaft 121 are rotatedclockwise as viewed in FIG. 1 to open the primary throttle valves 123.When the primary throttle valves are partly opened,

fuel is drawn from the central bowls 35L and 35R 9 the primary dischargenozzles 177 and mixed with air flowing through the primary barrels SSLand 55R. zAS

the level of fuel in the primary bowls 35L and 35R goes down, the needlevalves 107 associated with these bowls open up, and fuel is therebysupplied to the forward and rearward bowls 37L, 39L, 37R and 39R (whichmay be referred to as secondary bowls). These secondary bowls alreadybeing full, fuel immediately overflows therefrom and brings the fuellevel in the primary bowls back up to the level L1. At this point, thefloats 105 close the needle valves 107 to cut off further flow of fuelto the secondary bowls.

When the primary throttle valves 123 are opened to the point where thesecondary throttle valves 303 and 307 are opened, fuel is drawn from thesecondary bowls 37L, 39L, 37R and 39R as well as from the primary bowls35L and 35R. As the level of fuel goes down in the primary bowls, theneedle valves 107 open as above described, and fuel is supplied to thesecondary bowls. 'Ihese fill up, and then overflow into the primarybowls, thereby bringing the fuel in the latter back up to the level L1.

Opening of the forward and rearward secondary throttle valves 303 and307 is accomplished by means of the link 363 connecting the inner arm349 on the primary throttle shaft 121 at the right side of thecarburetor to the arm 365 on the rearward secondary throttle shaft 133,and by the link 369 connecting the arm 365 to the arm 371 on theright-hand end of the forward secondary throttle shaft 129. Thus, theforward and rearward secondary throttle valves are operated in unisonand in phase.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

We claim:

1. In a carburetor having a first mixture conduit and a. second mixtureconduit, vertically spaced first and second venturis in their respectiveconduits, nozzles to discharge fuel into their respective venturis, afirst reservoir for containing fuel to be supplied to the first conduit,a second reservoir for containing fuel to be supplied to the secondconduit, said second reservoir having a fuel inlet adapted to beconnected to a source of fuel, and a fuel outlet to supply fuel bygravity into the first reservoir when the head of fuel in the secondreservoir increases above a predetermined level, and means includiug avalve in said inlet for controlling the flow of fuel from said sourceinto said second reservoir to cut off flow of fuel from said source whenthe fuel in the first reservoir reaches a predetermined level below thelevel of fuel in the second resrvoir.

2. In a carburetor having a first mixture conduit and a second mixtureconduit, vertically spaced first and second venturis in their respectiveconduits, nozzles to discharge fuel into their respective venturis, afirst reservoir for containing fuel to be supplied to the first conduit,21 second reservoir for containing fuel to be supplied to the secondconduit, said second reservoir having a fuel inlet adapted to beconnected to a source of fuel, and a fuel outlet to supply fuel bygravity into the first reservoir when the head of fuel in the secondreservoir increases above a predetermined level, and means including avalve in said inlet for controlling the flow of fuel from said sourceinto said second reservoir to cut off flow of fuel from said source whenthe fuel in the first reservoir reaches a predetermined level below thelevel of fuel in the second reservoir, and a float in said firstreservoir to actuate said valve.

3. In a carburetor having a first mixture conduit and a second mixtureconduit, vertically spaced first and second venturis in their respectiveconduits, nozzles to discharge fuel into their respective venturis, afirst reservoir for containing fuel to be supplied to the first conduit,a second reservoir for containing fuel to be supplied to the secondconduit, said second reservoir having a fuel inlet adapted to beconnected to a source of fuel, and a fuel outlet to supply fuel bygravity into the first reservoir when the head of fuel in the secondreservoir increases above a predetermined level, and means including avalve in said inlet for controlling the flow of fuel from said sourceinto said second reservoir to cut off flow of fuel from said source whenthe fuel in the first reservoir reaches a predetermined level below thelevel of fuel in the second reservoir, and a float in said firstreservoir to actuate said valve, said fuel outlet comprising a partitionover which excess fuel flows from the second reservoir to said firstreservoir.

4. In a carburetor having a vertical primary mixture conduit and avertical secondary mixture conduit, a primary fuel system for supplyingfuel to the primary conduit at one elevation in said primary conduit, asecondary fuel system for supplying fuel to the secondary conduit at ahigher elevation in said secondary conduit, a primary bowl forcontaining fuel for the primary system, a secondary bowl for containingfuel for the secondary system, a partition providing a weir between saidbowls, said secondary bowl being adapted to be supplied with fuel from asource thereof, excess fuel supplied to said secondary bowl beingadapted to overflow therefrom into the primary bowl when it reaches apredetermined overflow level in said secondary bowl, and valve means forcontrolling the flow of fuel from said source to said secondary bowl andadapted to cut off flow of fuel from said source when the fuel in theprimary bowl reaches a predetermined level lower than said overflowlevel.

5. In a carburetor having a vertical primary mixture conduit and avertical secondary mixture conduit, a primary fuel system for supplyingfuel to the primary conduit at one elevation in said primary conduit, asecondary fuel system for supplying fuel to the secondary conduit at ahigher elevation in said secondary conduit, a primary bowl forcontaining fuel for the primary system, a secondary bowl for containingfuel for the secondary bowl being adapted to be supplied with fuel froma source thereof, excess fuel supplied to said secondary bowl beingadapted to overflow therefrom into the primary bowl when it reaches apredetermined overflow level in said secondary bowl, and valve means forcontrolling the flow of fuel from said source to said secondary bowl andadapted to cut off flow of fuel from said source when the fuel in theprimary bowl reaches a predetermined level lower than said overflowlevel, and a float in said primary bowl to actuate said valve meansresponsive to the level of fuel in the primary bowl.

6. In a carburetor having first, second and third mixture conduits, aventuri in each conduit, the venturis in said second and third conduitsbeing in a common horizontal plane above the venturi in the firstconduit, nozzles to discharge fuel into their respective venturis, afirst reservoir for containing fuel to be supplied to the first conduit,3. second reservoir for containing fuel to be supplied to the secondconduit, a third reservoir for containing fuel to be supplied to thethird conduit, said second and third reservoirs being adapted to besupplied with fuel from a source thereof and having overflow weirsadapted to supply excess fuel by gravity to the first reservoir, and avalve controlling the flow of fuel from said source and adapted to cutoff flow of fuel from said source when the head of fuel in the firstreservoir reaches a predetermined level below the fuel level in saidsecond and third reservoirs.

7. In a carburetor having first, second and third mixture conduits, aventuri in each conduit, the venturis in said second and third conduitsbeing in a common horizontal plane above the venturi in the firstconduit, nozzles to discharge fuel into their respective venturis, afirst reservoir for containing fuel to be supplied to the first conduit,a second reservoir for containing fuel to be supplied to the secondconduit, a third reservoir for containing fuel to be supplied to thethird conduit, said second and third reservoirs being adapted to besupplied with fuel from a source thereof and having overflow weirsadapted to supply excess fuel by gravity to the first reservoir, and avalve controlling the flow of fuel from said source and adapted to cutoff flow of fuel from said source when the head of fuel in the firstreservoir reaches a predetermined level below the fuel level in saidsecond and third reservoirs, said valve being actuated by a float in thefirst reservoir.

8. A carburetor having a vertical primary mixture and first and secondvertical secondary mixture conduits arranged in a row with the primaryconduit between the secondary conduits, a venturi in each conduit, afuel nozzle in each venturi, the venturi in the primary conduit beingspaced below the other venturis, a fuel container extending alongsidesaid conduits and divided into a primary bowl and first and secondsecondary bowls by first and second partitions, said primary bowl beinglocated between the secondary bowls alongside theprimary conduit, saidfirst and secondsecondary bowls being located alongside the first andsecond secondary conduits, said carburetor having a fuel inlet adaptedto be supplied with fuel from a source and passages from said inlet forsimultaneously supplying fuel to said secondary bowls, excess fuelsupplied to said secondary bowls being adapted to overflow therefromover said partitions when it reaches the top of said partitions, andfloat-controlled valvemeans including a float in said primary bowl forcontrolling flow of fuel from said inlet through said passages to saidsecondary bowls and adapted to cut 01f flow through said inlet when'thefuel in the primary bowl reaches a predetermined level below the top ofsaid partitions.

References Cited in the file of this patent UNITED STATES PATENTS1,323,786 Richard Dec. 2, 1919 1,449,664 Friz Marg27, 1923 1,586,097McCarthy et al May 25, 1926 2,420,925 Wirth May 20, 1947

